
Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. The vehicle
was designed and tested with top-quality brake parts.
When parts of the braking system are replaced — for
example, when the brake linings wear down and new
ones are installed — be sure to get new approved
replacement parts. If this is not done, the brakes might
not work properly. For example, if someone puts in brake
linings that are wrong for the vehicle, the balance
between the front and rear brakes can change — for the
worse. The braking performance expected can change in
many other ways if the wrong replacement brake parts
are installed.
Hydraulic Brake Pads
Brake pad lining life will vary depending on
vehicle application, working environment, equipment
maintenance, and style of driving. The brake pad lining
wear rate has to be monitored for individual driving
habits — original equipment linings have mechanical
wear indicators to help with this. When down to the last
10% of the brake lining, the brake lining wear indicator
rubs on the rotor, causing a scratching or chirping
sound. When this sound is heard, service to the brake
pads is needed. SeeScheduled Maintenance on
page 6-5.
Aftermarket brake linings might not meet the same
stringent requirements as the original equipment linings.
Using aftermarket brake linings can affect braking
performance, pedal feel, noise, and lining wear.
5-55

Electric Air Compressor
The vehicle might have an electric air compressor.
This compressor is used to run options that require
pressurized air, such as an air horn or air seat.
The air compressor is used when vehicles do not have
an air brake system.
The air supply for this
system must be
maintained by releasing
the drain valve to eject any
moisture that could have
built up in the system.
It is recommended that this system be drained on a
weekly basis.
Clutch Pedal Free Travel
If the vehicle has a V8 engine and a manual
transmission, the clutch needs adjustment when pedal
free travel gets down to about 1/4 inch (6 mm), as
measured at the clutch pedal pad. There should be
1 1/2 to 2 inches (38 to 51 mm) of clutch pedal
free travel.
If the clutch ever needs service, be sure to use only
approved clutch replacement parts.
Chassis Lubrication
The Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see the Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.
5-57

2. Push the release lever and slide the wiper assembly
toward the driver side of the vehicle.
3. Install a new blade by reversing Steps 1 and 2.
Other Service Items
Fuel Filter
Fuel Filter/Pressure Regulator
(Gasoline Engines)
The steel fuel filter/pressure regulator is located near
the engine compartment on the driver’s side frame rail.
If your vehicle has a rear steel fuel tank, the fuel
filter/pressure regulator is located near the rear fuel
tank, on the driver’s side frame rail. SeeScheduled
Maintenance on page 6-5for recommended service
intervals.
If your vehicle is equipped with the optional Davco
spin-on type filter, it is located on the driver’s side
frame rail.
Fuel Filter (Diesel Engines)
If you have a diesel engine, your fuel filter is located in
the engine compartment on the driver’s side of the
vehicle, or along the driver’s side frame rail. See “Fuel
Filter Replacement” earlier in this section for further
information.
Also seeScheduled Maintenance on page 6-5for
recommended service intervals.
5-72

{CAUTION:
If wheel studs are damaged, they can break. If all
the studs on a wheel broke, the wheel could come
off and cause a crash. If any stud is damaged
because of a loose-running wheel, it could be that
all of the studs are damaged. To be sure, replace
all studs on the wheel. If the stud holes in a wheel
have become larger, the wheel could collapse in
operation. Replace any wheel if its stud holes
have become larger or distorted in any way.
Inspect hubs and hub-piloted wheels for damage.
Because of loose running wheels, piloting pad
damage may occur and require replacement of the
entire hub, for proper centering of the wheels.
When replacing studs, hubs, wheel nuts or
wheels, be sure to use GM original equipment
parts.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after a time. The wheel could
come off and cause a crash. When you
change a wheel, remove any rust or dirt from
places where the wheel attaches to the
vehicle. In an emergency, you can use a
cloth or a paper towel to do this; but be sure
to use a scraper or wire brush later, if you
need to, to get all the rust or dirt off.
How Often to Check
Wheel tightness is so important you should have a
technician check nut tightness on all wheels with
a torque wrench after your first 100 miles (160 km), and
then 1,000 miles (1 600 km) after that. Be sure to
repeat this service whenever you have a tire removed
or serviced. SeeScheduled Maintenance on page 6-5
for further information.
5-83

Maintenance Schedule......................................6-2
Introduction...................................................6-2
Maintenance Requirements..............................6-2
Your Vehicle and the Environment....................6-2
How This Section is Organized.........................6-3
Part A: Scheduled Maintenance Services...........6-4
Using the Maintenance Schedule......................6-4
Scheduled Maintenance Supplements................6-4Scheduled Maintenance...................................6-5
Part B: Owner Checks and Services................6-26
At Each Fuel Fill..........................................6-26
At Least Twice a Year...................................6-27
At Least Once a Year...................................6-30
Part C: Recommended Fluids and
Lubricants................................................6-31
Part D: Maintenance Record..........................6-33
Section 6 Maintenance Schedule
6-1

How This Section is Organized
This maintenance schedule is divided into four parts:
“Part A: Scheduled Maintenance Services”explains
what to have done and how often. Some of these
services can be complex, so unless you are technically
qualified and have the necessary equipment, let
your dealer/retailer do these jobs.
Your dealer/retailer has trained and supported service
people that will perform the work using genuine parts.
{CAUTION:
Performing maintenance work on a vehicle can be
dangerous. In trying to do some jobs, you can be
seriously injured. Do your own maintenance work
only if you have the required know-how and the
proper tools and equipment for the job. If you have
any doubt, have a qualified technician do the work.
SeeDoing Your Own Service Work on page 5-5.To purchase service information, seeService
Publications Ordering Information on page 7-10.
“Part B: Owner Checks and Services”tells what
should be checked and when. It also explains what can
easily be done to keep the vehicle in good condition.
“Part C: Recommended Fluids and Lubricants”lists
some recommended products necessary to help
keep the vehicle properly maintained. These products,
or their equivalents, should be used whether you do the
work yourself or have it done.
“Part D: Maintenance Record”is a place to record
and keep track of the maintenance performed on
the vehicle. Keep the maintenance receipts. They may
be needed to qualify the vehicle for warranty repairs.
6-3

Part A: Scheduled Maintenance
Services
In this part are scheduled maintenance services which
are to be performed at the mileage intervals specified.
Using the Maintenance Schedule
We want to help keep this vehicle in good working
condition. But we do not know exactly how you will drive
it. You might drive very short distances only a few
times a week. Or you might drive long distances all the
time in very hot, dusty weather. You might use the
vehicle in making deliveries or in many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You might need
more frequent checks and replacements. So please read
the following and note how you drive. If you have any
questions on how to keep the vehicle in good condition,
see your dealer/retailer.
This part tells you the maintenance services that should
be done and when to schedule them.
When you go to your dealer/retailer for service, trained
and supported service people will perform the work
using genuine parts.The proper fluids and lubricants to use are listed in
Part C. Make sure whoever services the vehicle uses
these. All parts should be replaced and all necessary
repairs done before you or anyone else drives the
vehicle.
This schedule is for vehicles that:
•carry passengers and cargo within recommended
limits on the vehicle’s Certification or Tire
Information label. SeeLoading the Vehicle on
page 4-20.
•are driven on reasonable road surfaces within legal
driving limits.
•use the recommended fuel. SeeGasoline Octane
on page 5-6for gasoline engine vehicles orWhat
Fuel to Use on page 5-8for diesel engine vehicles.
Scheduled Maintenance
Supplements
If the vehicle has a Caterpillar®diesel engine, the owner
manual is supplemented by the Caterpillar®Diesel
Engine Operation & Maintenance Manual. If the vehicle
has an Allison Transmission
®, the owner manual is
supplemented by an Allison Transmission®Operator’s
Manual. Always refer to these manuals for related
maintenance services.
6-4

Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be repeated after 100,000 miles
(166 000 km) at the same intervals for the life of
this vehicle. The services shown after 100,000 miles
(166 000 km) should be repeated at the same miles (km)
after those intervals for the life of this vehicle.
Gasoline engine vehicles and some DURAMAX
®diesel
and Isuzu diesel engine vehicles have a computer
that lets you know when to change the engine oil. This
is not based on mileage, but on engine operation
and engine temperature. When the computer has
calculated that the oil needs changing, the Engine Oil
Life System will indicate that a change is necessary. See
Engine Oil Life System (Gasoline Engine) on page 5-35
orEngine Oil Life System (DURAMAX/Isuzu Diesel
Engines) on page 5-36orEngine Oil Life System
(Caterpillar Diesel Engine) on page 5-38.
The “Footnotes” at the end of this Maintenance
Schedule further explain maintenance services.
SeeService Publications Ordering Information on
page 7-10.
100 Miles (160 km)
❑Wheel stud nut service.(36)
1,000 Miles (1 600 km)
❑Wheel stud nut service.(36)
❑Rear axle air shift motor service.(10)
7,500 Miles (12 000 km)
❑Gasoline Engine Only: Check engine oil life system.
If engine oil and filter are changed, reset system. See
“Engine Oil (Gasoline Engine)” in the Index.(2) (8)
❑Check fluid levels (or every 3 months, whichever
occurs first).(1) (5)
❑Chassis lubrication service (or every 6 months,
whichever occurs first).(11)
❑Spring-to-axle U-bolts and shackle bolts service.(15)
❑Wheels and tires service.(14)
❑Hydraulic brake service (or every 6 months, whichever
occurs first).(6) (36)
❑Parking brake service (or every 6 months, whichever
occurs first).(21)
❑Air brake service (or every 6 months, whichever
occurs first).(32)
❑Air brake automatic slack adjuster service (or every
500 hours, whichever occurs first).(33)
6-5